A controlled deflection roll of the type schematically shown by the Appenzeller U.S. Pat. No. 2,908,964, Oct. 20, 1959, permits the rotative roll shell to float relative to the fixed stationary shaft extending through the shell. The relative positions of the shell and shaft are determined by the relative forces of the roll nip pressure and the hydraulic pressure between the shaft and the shell.
The Kusters U.S. Pat. No. 3,023,695, Mar. 6, 1962, shows that the externally extending ends of the controlled deflection roll shaft can be provided with hydraulic pressure elements applying force to the roll in the direction of the counter roll, and in this case it would be possible for the shaft itself to float radially inside the shell in dependence on the shell's internal pressure and the force applied to the extending ends of the internal shaft. To prevent this, this patent shows the use of self-aligning anti-friction bearings between the ends of the shaft and the roll shell.
In both of the above patents, the pressure rolling nip line pressure is uniformly transmitted to the shaft from the roll shell via a sealed body of hydraulic liquid between the shaft and shell and extending for the length of the roll on its side forming the nip with the counter roll.
By mechanically fixing positions of the ends of the stationary shaft coaxially within the shell roll, deflections of the roll shell and shaft occurring during the roll's operation are reflected only very slightly at the shaft ends and are only small angular deflections of the shaft ends relative to the roll shell ends.
In modern versions of such controlled deflection rolls it is desirable to be able to rotatively power the shell. Such a drive typically comprises an arrangement for locking the shaft against rotation at one end and providing its other end with a triple-race bearing, having an inner race non-rotatively engaging the shaft end, and outer race on which the shell rotates, and a power driven intermediate race coupled to the end of the roll shell by a drive coupling accommodating the slight angular deviations of the shaft's end outside of the bearing between the shaft and the shell.
Although such a coupling can handle the relatively small angular shaft end deviations involved by a controlled deflection roll having end bearings, it cannot operate under the larger bodily displacements involved by the shaft and its ends of a controlled deflection roll which does not use the end bearings and which permits the shaft to bodily displace in dependence on the play of the forces involved.
Instead of the longitudinally extending sealed body of hydraulic fluid working against the shell's inside to provide the characteristic uniform pressure lengthwise between the shaft and shell's inside, it is possible to provide the shaft with cylinders containing pistons bearing against the shell's inside via appropriate bearing shoes. With the cylinders provided with the same pressure, a uniform force is provided lengthwise throughout the extent of the roll. An example of this is schematically shown by the Kusters et al U.S. Pat. No. 3,131,625, May 5, 1964.
A roll not using end bearings has an advantage in that roll deflection is controlled throughout the entire length of the roll shell. It also has an advantage in that it permits a particularly sensitive adjustment of the nip line pressure and can keep this line pressure uniformly throughout the length of the shell even though the counter roll against which the roll shell works, itself deflects. The floating roll shell can deflect throughout its entire length to match the beam deflection of the counter roll. In some instances, the counter roll may be another controlled deflection roll.
The object of the present invention is to permit the use of the drive which heretofore could be used only for the controlled deflection roll having end bearings between the roll shell and shaft, so as to drive the shell of the type of controlled deflection roll which does not use end bearings.